The foam cannon is a great tool as it will add tons of suds and thick foam. It will loosen all the dirt making it easier to come off. I always foam the car, and then immediately follow and agitate it with a wash mit. That way you’re scrubbing any hard caked on dirt that might not have fallen off.
As far as the ceramic coating goes I am not too sure due to I have never ceramic coated anything so I am not familiar. Maybe @falcaineer or @shane@detailedreflections Can chime in and give you some insight. Can’t wait to see pictures!